Backlight apparatus, and a liquid crystal display (LCD) therewith

ABSTRACT

Dissipation of heat generated by a luminescent source, such as a fluorescent lamp, of a backlight apparatus and an LCD therewith is enhanced by providing a proximity section in a holder, making the hottest part the closest to the holder for efficient heat conduction.

This is a divisional of U.S. patent application Ser. No. 10/307,910filed Dec. 2, 2002 now U.S. Pat. No. 6,960,001.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention generally relates to a backlight apparatus, and aliquid crystal display (LCD), and especially relates to a backlightapparatus including a luminescent source that generates heat, such as afluorescent lamp, and an LCD that employs the backlight apparatus.

Conventionally, CRT (cathode-ray tube) displays have been used. Inrecent years, use of thin displays that employ an LCD panel has beenprogressing. Display quality of the LCD has been enhanced, andenlargement and higher brightness of the displays are desired fortelevision use, etc. With requirements of brighter LCDs increasing,demands are increasing for a backlight apparatus that can provide theillumination for the enlarged and brighter liquid crystal panel.

2. Description of the Related Art

Conventional LCDs have been used mainly by notebook PCs, when up toabout 13 inch displays are the main thrust with a screen brightness ofaround 150 cd/m2 and a resolution of XGA. FIG. 1 and FIG. 2 show an LCD1A that is an example of a conventional LCD.

The LCD 1A is configured with a liquid crystal panel 2A, a housing 5, abacklight apparatus 10A, etc. The housing 5 holds the liquid crystalpanel 2A and the backlight apparatus 10A through a resin frame 6 and abackboard 9. Here, the backlight apparatus 10A gives predeterminedbrightness to a display of the liquid crystal panel 2A by illuminatingthe liquid crystal panel 2A from the back.

The backlight apparatus 10A generally includes a fluorescent light bulb3 serving as a light source, a light guide board 4 that guides the lightfrom the fluorescent light bulb 3 to the liquid crystal panel 2A, and aholder 7 that reflects the light from the fluorescent light bulb 3 tothe light guide board 4, while supporting the fluorescent light bulb 3via a rubber holder.

In the fluorescent light bulb 3, mercury is enclosed in Ar gas or Negas, and, on the wall of the fluorescent light bulb 3, a fluorescentmaterial is applied. Mercury gas generates ultraviolet rays duringelectric discharge, and light is generated when the ultraviolet rays hitthe fluorescent material.

The light guide board 4, made from acrylic resin, collaborates with anoptical sheet 8 installed, and transmits the light from the fluorescentlight bulb 3 and distributes the light all over the liquid crystal panel2A. In the case of the LCD 1A that provides a relatively small screensize (about 13 inches), where no particularly high resolution and noparticularly high screen brightness are required, the backlightapparatus 10A is provided only on one side of the light guide board 4,and only one fluorescent light bulb 3 is provided.

A larger screen size, 14 to 15 inches, has been used for the monitor ofa desktop PC. FIGS. 3 and 4 show an LCD 1B that provides a relativelylarge screen size, for which resolution of SXGA and screen brightness ofabout 250 cd/m are required. For this reason, two backlight apparatuses10B are installed in the LCD 1B, such that one of the backlightapparatuses is provided on each side of the light guide board 4.Further, each backlight apparatus 10B includes two fluorescent lightbulbs 3. However, with infusion of DVD drives, users require that PCmonitors provide even larger screens and higher brightness for movieviewing and so on.

In order to increase the screen size and brightness, there is a problemto solve. That is, the fluorescent light bulb 3 provided in thebacklight apparatus 10B generates heat with luminescence. Especially inboth ends of the fluorescent light bulb 3 where electrodes areinstalled, temperature can rise higher than 120 degrees C., when a largeelectric current is provided in order to obtain a high brightness. Forthis reason, some conventional solutions provide a rubber holder made ofa heat-conductive material at both ends of the fluorescent light bulb 3,such that heat can be dissipated to the holder 7.

Nevertheless, the heat generated by the fluorescent light bulb 3 cannotbe sufficiently dissipated by the holder 7 via the rubber holder,causing lowering of the brightness of the fluorescent light bulb 3, andbreaking of a solder joint that connects the electrode section andwiring. Another solution has been to provide a larger holder 7 for moreefficient heat dissipation, however, it causes dimensions of the LCDs 1Aand 1B to become large.

The present invention is made in view of the above-mentioned point, andit aims at offering a backlight apparatus that can efficiently dissipatethe heat generated in the luminescent source, and an LCD that employsthe backlight apparatus.

SUMMARY OF THE INVENTION

It is a general object of the present invention to provide a backlightapparatus for a liquid crystal display (LCD), and a liquid crystaldisplay therewith that substantially obviate one or more of the problemscaused by the limitations and disadvantages of the related art.

Features and advantages of the present invention will be set forth inthe description that follows, and in part will become apparent from thedescription and the accompanying drawings, or may be learned by practiceof the invention according to the teachings provided in the description.Objects as well as other features and advantages of the presentinvention will be realized and attained by the backlight apparatus forthe LCD, and the LCD therewith particularly pointed out in thespecification in such full, clear, concise, and exact terms as to enablea person having ordinary skill in the art to practice the invention.

To achieve these and other advantages and in accordance with the purposeof the invention, as embodied and broadly described herein, theinvention provides, among other means, a proximity section in a holderthat holds the luminescent sources, which helps improve heatconductivity for a center part where the luminescent sources are closetogether, and the temperature is the highest. The proximity section thatis close to the luminescent sources has a space on its back side that isused to lay wiring, resulting in space saving. Where there are three ormore luminescent sources, one or two centrally positioned luminescentsources that tend to be the hottest are placed closer to the holder thanother luminescent sources, such that heat dissipation of the centrallypositioned luminescent sources is enhanced, resulting in an improvementof overall heat dissipation efficiency. Since the temperature of twoelectrode sections toward the ends of each of the luminescent sourcestends to be the highest, the distance between the luminescent source andthe holder in the longitudinal direction of the luminescent source ismade such that the distance is the smallest at the two ends, and thelargest at the center. This improves uniformity in brightness of theluminescent source. A supporting component is provided with a projectingsection such that the projecting section is thermally connected to ahousing such that the heat is dissipated effectively. The housing canprovide a concavity to contain the projecting section such that thethermally connecting area is increased, resulting in a higher efficiencyof the heat dissipation. A heat-dissipating component can be providedbetween the supporting component and a light guide board such that theheat dissipation is further improved. The supporting component can bemade of an insulating material such that a high electric current flowinginto the luminescent source is not discharged externally. Providing aprojecting section to the insulating material further suppressesundesired electric discharge.

The LCD of the present invention employs the backlight apparatus of thepresent invention, resulting in a reliable product that deliverssatisfactory image display at a high brightness, due to the highefficiency of the heat dissipation.

BRIEF DESCRIPTION OF THE DRAWINGS

FIGS. 1A and 1B are figures for explaining an LCD having a small screensize, which is provided with a conventional backlight apparatus;

FIG. 2 shows an expanded view of a portion indicated by an arrow A1 inFIG. 1;

FIGS. 3A and 3B are figures for explaining an LCD having a large screensize, which is provided with a conventional backlight apparatus;

FIG. 4 shows an expanded view of a portion indicated by an arrow A2 inFIG. 3;

FIG. 5 is a perspective diagram showing an LCD and backlight apparatusof a first embodiment of the present invention;

FIG. 6 is a sectional drawing showing a main part of the LCD andbacklight apparatus of the first embodiment of the present invention;

FIG. 7 is a sectional drawing showing a main part of the LCD andbacklight apparatus of a second embodiment of the present invention;

FIG. 8 is a sectional drawing showing a main part of the LCD andbacklight apparatus of the third embodiment of the present invention;

FIG. 9 is a plan showing the LCD and backlight apparatus of the fourthembodiment of the present invention;

FIG. 10 is an exploded and perspective diagram showing the LCD of thefifth embodiment of the present invention;

FIG. 11 is an exploded and perspective diagram showing the backlightapparatus of the fifth embodiment of the present invention;

FIG. 12 is a perspective diagram showing an expanded view of a main partof the backlight apparatus of the fifth embodiment of the presentinvention (No. 1);

FIG. 13 is a perspective diagram showing an expanded view of the mainpart of the backlight apparatus of the fifth embodiment of the presentinvention (No. 2);

FIG. 14 is a perspective diagram showing an expanded view of the mainpart of the backlight apparatus of the fifth embodiment of the presentinvention (No. 3);

FIG. 15 is an exploded and perspective diagram showing a main part of afluorescent light bulb assembly prepared in the LCD and backlightapparatus of the sixth embodiment of the present invention;

FIG. 16 is a perspective diagram showing a main part of the fluorescentlight bulb assembly prepared in the LCD and backlight apparatus of thesixth embodiment of the present invention;

FIG. 17 is a sectional drawing showing a principal part of thefluorescent light bulb assembly prepared in the LCD and backlightapparatus of the sixth embodiment of the present invention;

FIG. 18 is an exploded and perspective diagram showing a main part ofthe fluorescent light bulb assembly prepared in the LCD and backlightapparatus of the seventh embodiment of the present invention;

FIG. 19 is a sectional drawing showing a main part of the fluorescentlight bulb assembly prepared in the LCD and backlight apparatus of theseventh embodiment of the present invention;

FIG. 20 is a perspective diagram showing a main part of the fluorescentlight bulb assembly prepared in the LCD and backlight apparatus of theeighth embodiment of the present invention;

FIG. 21 is a front view showing a main part of the fluorescent lightbulb assembly prepared in the LCD and backlight apparatus of the eighthembodiment of the present invention;

FIG. 22 is a sectional drawing showing a main part of the fluorescentlight bulb assembly prepared in the LCD and backlight apparatus of theeighth embodiment of the present invention; and

FIG. 23 shows an expanded view near an insulation projection.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

In the following, embodiments of the present invention will be describedwith reference to the accompanying drawings.

A first embodiment will be described referring to FIG. 5 and FIG. 6 thatshow a backlight apparatus 20A, and an LCD 21A using the backlightapparatus 20A of the first embodiment of the present invention. The LCD21A includes a liquid crystal panel 22, a housing 25, etc. in additionto the backlight apparatus 20A. The housing 25 has a resin frame 26inside, which holds the liquid crystal panel 22. Further, a backboard 29is provided at a lower part of the resin frame 26, and the backlightapparatus 20A is arranged between the backboard 29 and the housing 25.

The backlight apparatus 20A gives predetermined brightness to thedisplay of the liquid crystal panel 22 by illuminating the liquidcrystal panel 22 from the back. The backlight apparatus 20A includes alight guide board 24 and a fluorescent light bulb assembly 40A. Further,the fluorescent light bulb assembly 40A includes a fluorescent lightbulb 23, a holder 27, a rubber holder 32, and wiring 33. In addition,the fluorescent light bulb assembly 40A is arranged such that it can bedetached from and attached to the main part of the backlight apparatus20A in order to facilitate maintenance service.

The fluorescent light bulb 23 is a cold cathode tube serving as aluminescent source. In the present embodiment, two fluorescent lightbulbs 23 are included in the fluorescent light bulb assembly 40A. In theglass tube of the fluorescent light bulb 23, mercury, Ar gas, and Ne gasare contained, and a fluorescent material is applied to the wall of theglass tube.

Inside each fluorescent light bulb 23, an electrode section 31 (notshown in FIG. 5, but shown in FIG. 15) is provided at each end. Wiring33 (not shown in FIG. 5, but shown in FIG. 10) that is connected to theelectrode section 31 is pulled out.

Although an electrode section 31 is arranged on each end of thefluorescent light bulb 23, as shown in FIG. 15, the wiring 33 is pulledout only from one side, and connected to a connector 36. Therefore, thewiring 33 includes a short pair of wires that connects the electrodesection 31 nearer to the connector 36, and a long pair of wires thatconnects the other electrode section 31 that is farther from theconnector 36. The long pair of the wires 33 connected to the electrodesection 31 on the far end is pulled out in the same direction as theshort pair of wires 33, running along the backside of the holder 27 asshown in FIG. 6.

When electricity is applied to the wiring 33, the electrode section 11discharges, and mercury gas generates ultraviolet rays, which hit thefluorescent material, resulting in emission of light. The fluorescentlight bulb 23 further includes a rubber holder 32, provided on the bothends of fluorescent light bulb 23. The holder 27 holds the fluorescentlight bulb 23 through the rubber holder 32.

The holder 27 is made from mainly metal materials such as SUS, steel,and aluminum, and is arranged in the longitudinal direction of thefluorescent light bulb 23. A silver vacuum evaporation layer or a whitereflective layer is formed on a face of the holder 27, the face facingthe fluorescent light bulb 23 such that the light from the fluorescentlight bulb 23 is reflected efficiently. In this manner, the light of thefluorescent light bulb 23 is efficiently guided to the light guide board24, without diffusing. Further, this holder 27 serves also as a heatdissipation component that radiates heat generated by the fluorescentlight bulb 23, as described later.

The rubber holder 32 is made of silicone rubber, for example, in whichhigh conductive metal powder is mixed as filler, providing high heatconductivity. The rubber holder 32 is provided at a positioncorresponding to each electrode section 11 of the fluorescent light bulb23. The rubber holder 32 also serves to hold the fluorescent light bulb23 to the holder 27 as mentioned above. Further, the rubber holder 32 isthermally connected to the holder 27 by being attached to the holder 27.

The light guide board 24 is made of a transparent resin, such as acrylicresin. The light guide board 24 is arranged to face the back of theliquid crystal panel 22. Further, as shown in FIG. 6, the fluorescentlight bulb 23 is arranged to face the side of the light guide board 24,i.e., light injecting side.

The optical sheet 28 is arranged in the front side of the light guideboard 24 that is, the side that faces the liquid crystal panel 22. Theoptical sheet 28 condenses and spreads the light emitted from the lightguide board 24, such that the light is efficiently provided to theliquid crystal panel 22. Further, a reflective sheet 30 is arranged onthe backside of the light guide board 24. The reflective sheet 30reflects that portion of the light that leaks from the light guide board24, and returns the leaking light to the interior of the light guideboard 24.

Next, an explanation follows about a structure of the holder 27 thatserves as a main part of the present embodiment with reference to FIG.6. The holder 27 of the present embodiment is characterized by providinga proximity section 41 at a location in the proximity of the fluorescentlight bulb 23 (luminescent source).

The proximity section 41 is formed by press processing the holder 27,and, therefore, can be formed simultaneously with fabrication of theholder 27. For this reason, manufacturing and assembling of thebacklight apparatus 20A do not become complicated even if the proximitysection 41 is formed in the holder 27.

By the way, the position where temperature rises the most caused by heatgenerated by the fluorescent light bulbs 23 in the fluorescent lightbulb assembly 40A is where the fluorescent light bulbs 23 face eachother, i.e., the position where each fluorescent light bulb 23 adjoinsthe other fluorescent light bulbs 23. The present embodiment providesthe proximity section 41 in the holder 27 at the position where thetemperature rises the most, the proximity section 41 facing thefluorescent light bulbs 23.

By the structure as described above, the distance between thefluorescent light bulb 23 and the holder 27 becomes small, whichincreases efficiency of heat dissipation of the heat generated by thefluorescent light bulb 23 through the proximity section 41 and theholder 27. In this manner, the temperature rise of the fluorescent lightbulb 23 is reduced. Especially, as mentioned above, since the proximitysection 41 absorbs the heat of the part where the temperature rises themost due to the heat generated by the fluorescent light bulb 23, andradiates the heat through the holder 27, decrease in brightness of thefluorescent light bulb 23 due to heat is minimized. Further, byperforming heat dissipation as mentioned above, the temperature rise ofthe light guide board 24 by the fluorescent light bulb 23 is suppressed,which prevents deformation and fusion that may otherwise occur in thelight guide board 24.

Further, since the heat generated by the fluorescent light bulb 23 isdissipated efficiently by the backlight apparatus 20A of the presentembodiment, high brightness is realized. Therefore, according to LCD 21Ausing this backlight apparatus 20A, high reliability is realized while agood picture display of high brightness is provided.

Although the backlight apparatus 20A having two fluorescent light bulbs23 is explained above as an example, the present invention can apply toa backlight apparatus having any number of fluorescent light bulbs 23,the number including 1 and 3.

Further, although the proximity section 41 is provided nearby a middlepoint of the two fluorescent light bulbs 23 in the present embodiment,when the temperature distribution in a fluorescent light bulb assemblyis known, it is effective to form the proximity section 41 near the partwhere the temperature becomes the highest.

Next, a second embodiment of the present invention is explained.

FIG. 7 shows a backlight apparatus 20B, and an LCD 21B using thebacklight apparatus 20B of the second embodiment. Here, in FIG. 7, aboutthe same components as shown in FIG. 5 and FIG. 6 in the firstembodiment, the same reference numbers are attached and the explanationthereof is not repeated. This practice will apply to explanations anddrawings of the third embodiment et seq., to be described later.

The proximity section 41 of the backlight apparatus 20B of the presentembodiment is formed in a middle position of the pair of fluorescentlight bulbs 23, like the first embodiment, where the temperature becomesthe highest in the fluorescent light bulb assembly 40B. The secondembodiment is characterized by providing the wiring 33 of thefluorescent light bulb 23 on a side of the proximity section 41 otherthan the side to which the fluorescent light bulb 23 faces. Thisposition will be hereafter called the backside.

As described above, the wiring 33, which includes the short pair ofwires and the long pair of wires, connected to the electrode sections 31is pulled out to the same direction, with the long pair of wires runningon the back side of the holder 27. In the present embodiment, the longpair of wires of the wiring 33 provided on the backside of the holder 27is arranged in the back position of the proximity section 41.

Miniaturization of the backlight apparatus 10B is attained by thisconfiguration. That is, as mentioned above, since the proximity section41 is formed close to the high-temperature part of the fluorescent lightbulbs 23, a space becomes available in the backside position. Comparedwith a configuration that arranges this wiring 33 in other parts,miniaturization of the backlight apparatus 20B can be attained becausethe space is available for arranging the long pair of wires of thewiring 33 that is connected to the electrode section 31.

Although the proximity section 41 gets heated while dissipating the heatgenerated by the fluorescent light bulbs 23, a heat-resistant materialis used as a covering material of the wiring 33. In this manner, metallines of the wiring 33 are not exposed by the covering material meltingdue to high temperature.

Next, the third embodiment of the present invention is explained.

FIG. 8 shows a backlight apparatus 20C, and an LCD 21C using thebacklight apparatus 20C of the third embodiment of the presentinvention.

The backlight apparatus 20C of the third embodiment includes threefluorescent light bulbs 23 (designated 23A, 23B, and 23C), in order toattain high brightness. As shown in FIG. 8, the fluorescent light bulb23B is provided in the middle of the three fluorescent light bulbs 23A,23B, and 23C. The present embodiment is characterized by having arrangedthe fluorescent light bulb 23B closer to the holder 27 than the otherfluorescent light bulbs 23A and 23C. Positions of the fluorescent lightbulbs 23A, 23B, and 23C can be relatively easily determined by arrangingsupporting holes for the fluorescent light bulbs 23A, 23B, and 23C,which are formed on the holder 27.

By the way, when three or more fluorescent light bulbs are provided, thefluorescent light bulb located in the middle has the most intensetemperature rise. In the configuration of the present embodiment thatuses the three fluorescent light bulbs 23A, 23B, and 23C, thetemperature of the fluorescent light bulb 23B located in the middlebecomes the highest.

Accordingly, in the present embodiment, the fluorescent light bulb 23Bis placed near the holder 27. In this manner, the heat of thefluorescent light bulb 23B is better dissipated than other fluorescentlight bulbs 23A and 23C. In this manner, the heat generated by thefluorescent light bulb 23B is efficiently dissipated through the holder27. As the result, the temperature rise of the whole backlight apparatus20C can be suppressed.

Although a configuration of the fluorescent light bulb assembly 40C isdescribed as including the three fluorescent light bulbs 23A, 23B, and23C in the present embodiment, the present invention can be applied to afluorescent light bulb assembly having four or more fluorescent lightbulbs.

Next, the fourth embodiment of the present invention is explained.

FIG. 9 shows a backlight apparatus 20D, and an LCD 21D using thebacklight apparatus 20D of the fourth embodiment. The present embodimentis characterized by a tapering shape of the space between the holder 27Aand the fluorescent light bulb 23, which are included in the fluorescentlight bulb assembly 40D. The space is the widest at the center of thefluorescent light bulb 23, and decreases in width toward each end(henceforth both-end positions) of the fluorescent light bulb 23, wherethe electrode section 31 is formed.

Specifically, since the diameter size of the fluorescent light bulb 23is uniform over its longitudinal direction, the holder 27 is structuredsuch that the space at the both-end positions is set small (A2 in FIG.9), while the space at the center is set large (A1 in FIG. 9). Byemploying this structure, the space between the fluorescent light bulb23 and holder 27A at the both-end positions is set at a2, and the spacebetween the fluorescent light bulb 23 and the holder 27A at the centeris set at a1, where a1>a2.

According to the structure described above, efficiency of heatdissipation is heightened at the both-end positions, in comparison withthe center. As a result, heat distribution is made relatively uniformover the longitudinal direction of the fluorescent light bulb 23,realizing relatively uniform distribution of brightness of the backlightapparatus 20D.

Another advantage of the above structure is that inserting into andremoving the fluorescent light bulb assembly 40D from the housing 25 isfacilitated. That is, in the backlight apparatus 20D of the presentembodiment, the fluorescent light bulb assembly 40D has the smallerdimension a2 at the both ends (namely, both ends of the holder 27A) thanthe center part, and the size of a hole prepared in the housing 25, intowhich the fluorescent light bulb assembly 40D is inserted, is made toaccept the larger dimension a1, which is larger than a2.

As above, it is easy to insert the smaller end of the fluorescent lightbulb assembly 40D into the insertion hole of the housing 25, which ismade the larger.

Next, the fifth embodiment of the present invention is explained.

FIG. 10, FIG. 11, FIG. 12 and FIG. 13 show a backlight apparatus 20E,and an LCD 21E using the backlight apparatus 20E of the fifthembodiment.

FIG. 10 is an exploded and perspective diagram of the LCD 21E of thefifth embodiment. As shown in FIG. 10, the LCD 21E of the presentembodiment provides the liquid crystal panel 22 on the backlightapparatus 20E, with the housing 25 provided on the top. Further, thestructure is such that the fluorescent light bulb assembly 40E isinserted into and removed from the backlight apparatus 20E. In addition,a data substrate 34 and a gate substrate 35 are provided on separatesides of the liquid crystal panel 22.

FIG. 11 is an exploded and perspective diagram expanding and showing thebacklight apparatus 20E.

The backlight apparatus 20E of the present embodiment includes a lightguide board 24, an optical sheet 28, and a reflective sheet 30 that arecontained in a housing (case) structured by a frame 37 located in theupper part, and a bottom metal plate 46 located in the lower part.Further, a fluorescent light bulb assembly 40E is also contained in thehousing. For this reason, an insertion concavity 38 is formed in theframe 37, and a guiding concavity 49 is formed in the bottom metal plate46.

Furthermore, a bent section 48 is formed in an end section of theguiding concavity 49 of the bottom metal plate 46. The bent section 48is structured as a part of the bottom metal plate 46, forming one body,and is simultaneously formed when the guiding concavity 49 and a sideplate 47 are formed. Here, as a material for the bottom metal plate 46,a metal material with high thermal conductivity is selected.

Details will be described about an end of the fluorescent light bulbassembly 40E, the end being the first part inserted into the housing.The end is the left-hand side end of the fluorescent light bulb assembly40E in FIG. 11. As shown in FIG. 12, the fluorescent light bulb assembly40E of the present embodiment includes a fluorescent light bulb 23, aholder 27B, and a rubber holder 32A. Here, the structure is such thatthe rubber holder 32A that holds the fluorescent light bulb 23 to theholder 27B projects from an edge 42 of the holder 27B (toward the bentsection 48). The part that projects from the edge 42 of the rubberholder 32A is hereafter called a first projecting section 44.

On the other side of the fluorescent light bulb assembly 40E, withreference to FIG. 13 (reverse angle), a through hole 43 is formed on theholder 27B, such that the through hole 43 faces the side plate 47 (apart of the bottom metal plate 46. A part of a rubber holder 32Bprojects from the through hole 43. The projected part is called a secondprojecting section 45.

In the backlight apparatus 20E that is structured as above, when thefluorescent light bulb assembly 40E is inserted to a predeterminedposition in the housing constituted by the frame 37 and the bottom metalplate 46, the first projecting section 44 is thermally connected bycontacting the bent section 48 formed in the bottom metal plate 46.Further, the second projecting section 45 is thermally connected to theside plate 47 of the bottom metal plate 46.

In this manner, the heat generated by the fluorescent light bulb 23 isdissipated by the bottom metal plate 46 through the first and the secondprojecting sections 44 and 45, and by the holder 27B. Specifically, therubber holder 32A is thermally connected to the bottom metal plate 46,by the first projecting section 44 contacting the bent section 48 on theleft-hand side in FIG. 12. Further, on the other side, the rubber holder32B is thermally connected to the bottom metal plate 46, by the secondprojecting section 45 contacting the side plate 47.

As above, the heat generated by the fluorescent light bulb 23 isefficiently dissipated, and the temperature rise of the fluorescentlight bulb 23 can be reduced. Especially, because the first projectingsection 44 and the second projecting section 45 are arranged at bothends of the fluorescent light bulb 23, where the temperature becomes thehighest, the fluorescent light bulb 23 is cooled effectively.

Furthermore, in the present embodiment, the first projecting section 44provided on the left-hand side edge does not slide on, nor contact with,the side plate 47 when the fluorescent light bulb assembly 40E isinserted, such that the first projecting section 44 does not wear frominsertion friction. The second projecting section 45 that is to contactthe side plate 47 is provided in a position where the distance to slideon the side plate 47 when being inserted is short, such that wear of thesecond projecting section 45 by insertion friction is minimized.

Although the second projecting section 45 and the side plate 47 thatface each other take a flat shape in the above-mentioned embodiment asshown in FIG. 13, a concavity section 50 may be provided in the sideplate 47 at a predetermined position as shown in FIG. 14, such that thesecond projecting section 45 meets the concavity 50 when the fluorescentlight bulb assembly 40E is installed.

The concavity 50 is formed such that the second projecting section 45 isenclosed, as shown by the mark (B) in FIG. 14. In this manner, the areawhere the second projecting section 45 contacts the concavity 50 becomeslarge, resulting in a higher heat dissipation efficiency, andsuppressing temperature rise of the fluorescent light bulb 23.

Next, the sixth embodiment of the present invention is explained.

FIG. 15, FIG. 16 and FIG. 17 show a fluorescent light bulb assembly 40Fused in a backlight apparatus and an LCD of the sixth embodiment. Thefluorescent light bulb assembly 40F of the present embodiment ischaracterized by providing a heat dissipating piece 51 between therubber holder 32 and the light guide board 24, such that the heatdissipating piece 51 is thermally connected with a holder 27C, as shownin FIG. 17.

In the present embodiment, a structure is such that the heat dissipationcomponent section 51 is provided at an edge of the holder 27C in onebody, as shown in FIG. 15. Then, the wiring 33 that is beforehandconnected to the fluorescent light bulb 23 and a flange 36 is equippedto the rubber holder 32 that is, in turn, installed in the holder 27C,as shown in FIG. 16. Then, the heat dissipation component section 51 isbent and processed in a direction indicated by an arrow, such that therubber holder 32 is surrounded by the holder 27C and the heatdissipation component section 51. Therefore, when the fluorescent lightbulb assembly 40F is installed in the housing (not shown) of thebacklight apparatus, the heat dissipation component section 51 comesbetween the rubber holder 32 and the light guide board 24.

Thus, by providing the heat dissipation component section 51 that isthermally connected with holder 27C between the rubber holder 32 and thelight guide board 24, the heat generated by the fluorescent light bulb23 is not conducted from the rubber holder 32 to the light guide board24, but is conducted to the holder 27C through the heat dissipationcomponent section 51. In this manner, the light guide board 24 isprevented from being damaged by the heat generated by the fluorescentlight bulb 23, and a reliable backlight apparatus is realized.

As mentioned above, in the present embodiment, since the heatdissipation component section 51 is provided in one body with the holder27C, the number of components does not increase. Further, the one bodystructure of the heat dissipation component section 51 and the holder27C contributes to higher heat conductivity from the heat dissipationcomponent section 51 to the holder 27C.

Next, the seventh embodiment of the present invention is explained.

FIG. 18 and FIG. 19 show a fluorescent light bulb assembly 40G used in abacklight apparatus and an LCD of the seventh embodiment.

In the sixth embodiment, the heat dissipation component section 51 isformed in one body with the holder 27C. Here, in the seventh embodiment,a clip component 52, as shown in FIG. 18 and which is called aheat-dissipating clip 52, is employed to help dissipate heat. Theheat-dissipating clip 52 is made of a metal material that has highthermal conductivity and elasticity.

Accordingly, the heat-dissipating clip 52 is attachable to anddetachable from the holder 27, facilitating assembly and maintenance.

Next, the eighth embodiment of the present invention is explained.

FIG. 20, FIG. 21, FIG. 22, and FIG. 23 show a fluorescent light bulbassembly 40H used by a backlight apparatus and an LCD of the eighthembodiment.

The fluorescent light bulb assembly 40H of the present embodiment isstructured such that the rubber holder 32C is made of an insulatingmaterial, and an insulator projection 53 is provided to the rubberholder 32C. The insulator projection 53 is formed in one body with therubber holder 32C, and is formed between the electrode section 31 of thefluorescent light bulb 23, and the holder 27, as shown in FIG. 21, FIG.22, and FIG. 23. Further, the insulator projection 53 is formed only ina position facing the holder 27, and is not formed in a position facingthe light guide board 24, as shown in FIG. 20 and FIG. 22.

Here, the holder 27 is made of a metal material as described above, anda large electric current flows through the electrode section 31,generating electric discharge. For this reason, a possibility is thatelectric discharge may occur between the electrode section 31 and theholder 27. In order to attain high brightness, a large electric currentis required, which increases the possibility of external electricdischarge occurring. When the external electric discharge occurs, metalparticles are affixed to the inner wall of the fluorescent light bulb 23by sputtering, causing remarkable degradation of the fluorescent lightbulb 23, and reliability of the backlight apparatus will fall.

In view of this, the present embodiment provides the insulatorprojection 53 to the rubber holder 32C that insulates the electrodesection 31 from the holder 27. In this manner, a route for the electricdischarge to occur becomes long as an arrow shows in FIG. 23, andtherefore, occurrence of the electric discharge is suppressed, enhancingsafety and reliability of the backlight apparatus.

Further, in the present embodiment, since the insulator projection 53 isprovided only in an area where the electric discharge may occur betweenthe electrode section 31 and the holder 27, and where the insulatorprojection 53 faces the holder 27, the light directed to the light guideboard 24 of the fluorescent light bulb 23 is not interrupted. Therefore,even if the insulator projection 53 is provided in order to prevent theelectric discharge from occurring, the brightness of the backlightapparatus is not lowered.

According to the present invention, various effects are realized asfollows.

By providing the proximity section in the holder, dissipation efficiencyof the heat generated by the luminous source is improved.

By providing the space for wiring on the backside of the holder,miniaturization of the backlight apparatus is realized.

By locating the centrally positioned luminescent source elements thattend to be the hottest closer to the holder, temperature rise of theluminescent source as the whole is suppressed, resulting in efficientheat dissipation.

By providing the tapering shape such that the distance between theluminescent source and the holder is the largest at the central point ofthe luminescent source, and is the smallest at both ends of theluminescent source, relatively uniform heat distribution is attained,and, therefore, relatively uniform brightness of the luminescent sourceis obtained.

By providing the projecting section to the holder, conductivity of theheat generated by the luminescent source is improved, resulting inenhanced heat dissipation, and suppressing a temperature rise of theluminescent source.

By providing the concavity shape for the projecting section, thecontacting area is increased, which further improves heat conductivity,resulting in further ability to suppress the temperature rise of theluminescent source.

By providing the heat dissipation component, dissipation of the heatgenerated by the luminescent source is enhanced, preventing the lightguide board from being damaged, and realizing a reliable backlightapparatus.

By providing the heat dissipation component in one body with the holder,the number of components is minimized.

By providing the heat dissipating clip that is attachable anddetachable, assembly and maintenance is facilitated.

By providing the insulator projecting section, external electricdischarge between the electrode section of the luminescent source andthe holder is suppressed, enhancing safety and reliability of thebacklight apparatus.

By providing the insulator projecting section such that the light fromthe luminescent source is not interrupted, brightness of the backlightapparatus is not lowered.

By using the backlight apparatus of the present invention, an LCD thatprovides enhanced image quality with high reliability is realized.

Further, the present invention is not limited to these embodiments, butvarious variations and modifications may be made without departing fromthe scope of the present invention.

The present application is based on Japanese priority application No.2001-399592 filed on Dec. 28, 2001 with the Japanese Patent Office, theentire contents of which are hereby incorporated by reference.

1. A backlight apparatus of an edge light type, comprising: at least oneluminescent source having an electrode section for conducting electriccurrent, a holder in which the luminescent source is provided, a housingin which the holder is provided, and a supporting component made from aninsulating material attached to the luminescent source for supportingthe luminescent source in the holder and partially enclosing theelectrode section of the luminescent source, said supporting componenthaving an insulator projection section such that the insulatorprojection section comes between a part of the electrode section of theluminescent source that is not enclosed by the supporting component andthe holder.
 2. The backlight apparatus as claimed in claim 1, whereinthe insulator projection section is formed only in a position that facesthe holder.